#include <stdio.h>
#include <math.h>
#define PI 3.141592
int main(int argc, char *argv[]) {

    double r = 0;
    while (scanf("%lf",&r)!=EOF)
    {
        double v = (4.0 / 3.0) * PI * pow(r, 3);
        printf("%.3lf\n", v);
    }
    return 0;
}